Transfer machines



31, 1957 o. w. BARKER ET AL 8,

TRANSFER MACHINES Original Filed Jan. 51, 1952 4 Sheets-Sheet 1 IN V ENTORS rrin ZZZ Barker, Q @5356 [ewe/"Z.

Dec. 31, 1957 o. w. BARKER ET AL 0 TRANSFER MACHINES Original Filed Jan.:51; 1952 4 Sheets-Sheet 2 IN V EN TORS. 022'; 03 Zarfier, BY Jasqvb JZenert.

Muzzy 1957 o. w. BARKER ETAL TRANSFER MACHINES 4 Sheets-Sheet 3 OriginalFiled Jan. 31, 1952 Di -U i m L- I INVENTORS'. Orr/'27 {a Barker, 5 4 ByJase vi J Zane/g Wille Dec. 31, 1957 o, w. BARKER ET AL 2,818,002

TRANSFER MACHINES 4 Sheets-Sheet 4 Original Filed Jan. 31, 1952INVENTORS arr/'12 M Barker, BY Jw'e b J Zenerl.

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United States Pate TRANSFER MACHINES Orrin W. Barker, New Berlin, andJoseph J. Lenert, Milwaukee, Wis., assignors to Kearney & TreckerCorporation, West Allis, Wis., a corporation of Wisconsin Originalapplication January 31, 1952, Serial No. 269,191,

now Patent No. 2,749,811, dated June 12, 1956. Divided and thisapplication January 10, 1956, Serial No. 558,384

14 Claims. (Cl. 90-59) This invention relates generally to machinetools, and has more particular reference to an improved clampingmechanism especially adapted for use on transfer type machine tools.This patent application constitutes a division of our copending patentapplication, Serial No. 269,191, filed January 31, 1952 entitledTransfer Machines, which has issued as U. S. Patent No. 2,749,811, datedJune 12, 1956.

A general object of the present invention is to provide an improvedclamping mechanism adapted to receive and hold a workpiece in apredetermined exact position.

Another object of this invention is to provide an improved clampingmechanism for securing workpieces after they have been positioned,without displacing them from their position.

Another object of this invention is to provide an improved clampingmechanism operative to effect a clamping action on a workpiece from foursides.

Another object of the present invention is to provide an improvedclamping mechanism wherein the end clamping elements that operate in thepath of travel of the workpiece, are automatically moved to aninoperative position after releasing the workpiece so as not tointerfere with the movement of the workpiece to its succeeding station.

Still another object of this invention is to provide an improvedclamping mechanism capable of receiving a workpiece, positioning theworkpiece in an exact desired position, and clamping the workpiece insuch position.

A further object of the present invention is to provide an improvedclamping mechanism adapted to function in timed relationship with otheroperative members of a transfer type machine tool.

According to this invention there is provided an improved clampingmechanism wherein clamping of a workpiece is eiiected by clampingelements acting on four sides ofthe workpiece. The clamping elements onone of the sides are stationary and function as positive locatingelements for the workpiece as well as stops for cooperating with themovable clamping elements to secure the workpiece in position. Theclamping elements on the opposite side are movable, and when actuated,exert a lateral force on the workpiece to positively insure that theworkpiece is located against the stationary side clamping elements andto securely clamp the workpiece in the desired position. The ends of theworkpiece are securely held by clamping elements that are secured torotatable members which, when actuated, pivot the clamping members intooperating position at either end of the workpiece. One of the endclamping members is positively located in relation to the longitudinalaxis of the workpiece, while the opposite end member is movablelongitudinally towards the locating member to effect the clampingaction. Thus, the workpiece is positively located longitudinally andeffectively clamped in this position. In releasing the clampingmechanism, the movable side members are pivoted outwardly'to release thelateral clamping force while the movable end clamping member 'main frameor bed 15 rigidly supporting 21 is moved longitudinally away from theworkpiece thereby releasing the end clamping forces. The two endclamping elements are then pivoted to an out of the way position toclear the path of travel of the workpiece.

The foregoing and other objects of this invention will become more fullyapparent from the following detailed description, and may he achieved bythe exemplifying apparatus depicted in and further described in detailin connection with the accompanying drawings, in which:

Figure l is a view in front elevation of a transfer type milling machinein which the present invention is incorporated;

Fig. 2 is an enlarged detail view in front elevation of a clamping unitwith portions broken away to reveal the internal structure;

Fig. 3 is a view in vertical section taken along the plane representedby the line 3-3 in Fig. 2;

Fig. 4 is an endview of the clamping mechanism of Fig. 2 with partsbroken away to show the internal actuating mechanism for one of themovable side clamps; and,

Fig. 5 is a diagrammatic view illustrating the hydraulic circuit of theillustratedtransfer type machine tool in which the present invention hasbeen incorporated.

Referring more specifically to the drawings and particularly to Fig. 1thereof, the invention is shown embodied in a milling machinecomprising, in general, a

pair of clamping units 16 and 17 located in juxtaposition on the centralportion of the bed in predetermined position. The clamping units 16 and17 are disposed between two conveyors 18 and 19 mounted on either end ofthe bed 15, for carrying workpieces to and from the clamping units. Theconveyor 18 serves to receive the workpieces to be operated upon andmove them into position to be trans ferred to the clamping unit 16 wherethe first machining operation is performed. The completed workpieces aretransferred (in a manner to be described) from the clamping unit 16 tothe clamping unit 17 and thence to the conveyor 19 which functions todischarge them from the machine.

Adjacent to the main bed 15 and permanently secured thereto in parallelrelationship is a secondary bed (not shown) upon which is slidablysupported a saddle (not shown) to which is secured a pair of spindlehead units 25 and 26 that are utilized for moving the workpieces andeifecting the cutting operation. The saddle is movable longitudinally inits path of travel by any well known means, such as a piston andcylinder mechanism.

The conveyor unit 18 includes a conveyor frame 27 to which rollers 28and short rollers 29 are mounted by means of roller shafts 30 and shortroller shaft 31, respectively, and spaced apart so that the workpiececan be moved along the conveyor 18 with each roller successively takingup the load.

At the inner end of the conveyor 18 is a spring actuated stop mechanism(not shown) which stops the forward movement of the workpiece to controlthe workpieces admitted into the machine. Lateral movement of theworkpieces is limited by longitudinal guide bars 39, one of which isshown, disposed on either side of the rollers 28 and 29.

Upon being stopped by the spring actuated stop mechanism, the workpieceremains in this position until the stop is depressed by a cam .40,mounted on the movable saddle, and urging it downwardly when the saddlereaches the end of the cutting stroke, thus clearing the path formovement of the workpiece to its next succeeding station.

Upon being stopped by the stop mechanism, the workpiece is maintained ina properly aligned position by the longitudinal guide bars 39 and thestop, for receiving a transfer pin 45, carried by the spindle head unit25,

the transfer pin'being movable axially to enter a suitable opening (notshown) formed in the workpiece. Thus, the transfer pin 45 serves to linkthe workpiece to the spindle head unit 25, and as .the. lattermovesinits return stroke, after completing a cutting operation, it pullsthe workpiece with it to its nextstation.

In this manner the workpiecefis. transferred .from..the conveyor 18 tothe clamping unit'16 and then on its next movement into the similarclamping unit 17, both being secured to the bed 15 by any well knownmeans. such as bolts or welding. These clamping units serve toaccurately position the workpiece in a predetermined desired positionand .to hold the workpieces in place during the machining process.Foramore.:detaileddescription of the machine tool illustrated inconnection with the present invention reference may .be made :to thepreviously mentioned, U. S. Patent No. 2,749,811. Inasmuch as bothclamping units 16 and Y177 are identical, the construction and operationof only .one will Zbe described.

Referring to Eigs. 2 3 and 4, it can be seen that the workpiece isheld-inplacebyend clamps 46 and 47,.and side clamps 48, 49, 50 and 51,and of these clamps 46, 47, 5t) and 51 are movable forthe purpose ofapplying the clamping force to the workpiece, while the side clamps 48and 49 are stationary. Clamps 46-and 47 are pivotable laterally .to aposition below the base ofthe workpiece to .permit passage of =theworkpiece.

As previously stated, the clamping unit 16'is secured to the bed in apredetermined desiredposition, so that the gripping faces ofthestationary clamps '48 and 49 are disposed to align the workpiece sothat the portion of the workpiece to be operated on is in longitudinalalignment with the center lineof the path of travel of thecuttingelements carried by'the spindle head units and 26. Uponcompletion of a cutting operation the transfer pin 45 of the spindlehead unit 25 engages the workpiece to couple the workpiece to thespindle unit 25 and the latter is then actuatedin its return stroke,drawing the workpiece with it from the conveyor 18 to the clamping unit16. However, in being moved there is a possibility thatthe "workpiecewill be shifted out of the desired position. Therefore, when the workpiece is moved into the clamping unit '16, and the clamp ing unitactuated, 'the movable clamps '50, and 51 will contact the workpiece tomove it in position against the faces of the stationary clamps 48and49."Thus, positive lateral positioning of'the workpiece in a predetermineddesired position is assured.

Clamp 46 is welded onto a,.sleeve..52 and .clamp 47 is welded to asleeve 53, wherebytall pivotal.movements of these clamps are controlled.by the sleeves both of which are slidably and rotatably. mounted on apiston rod 54, and are interconnected for simultaneous rotationalmovement through cooperating clutch teeth 55.

and 56. This type of connection allows limited longitudinal movement ofthe sleeves while remaining in contact with each other therebypermitting one-sleeve to rotate the othersleeve aboutthe-piston rod 54.

In Fig. 3, there is shown. a hydraulic acuating mechanism for rotatingthe sleeves .52 and 53 to pivot'theend clamps 46 and 47 clear, of thepathof the workpiece. A hydraulic cylinder 57, with a doubleactingipiston .58 within, is .the. original source of the rotational(force to the sleeves 52andi53. .The;sleeve SZis'provided with agear'portion5i9catone end disposed to'mesh with a gear rack 590 formedonthe-piston 58, so-that any'movement of the piston 58 within thehydraulic cylinder 57 will rotate the sleeve 52 which, in turn, rotatesthe sleeve 53, thereby effecting pivotal movement of the clamps '46 and47 into or out .of position.

As clearly shown in Fig.2, theslongitudinal positioning and clampingof'the workpiece is, accomplished by means of the piston rod '54. Oneend of the piston rod 54 is 'to'the clamp 47by nut'61 and lock-'nut'62.'Thus,"whenever the piston 60 is moved by hydraulic pressure to theright, as viewed in Fig. 2, a longitudinal movement of the end clamp 47away from the end clamp 46 will occur, releasing the clamping pressureexerted on the workpiece by clamp 47 through an adjustable stud 63. Withthe end clamping pressure released, the end clamps 46 and 47 may bepivoted out of the path of the workpiece by rotating thesleeves'SZand.53.as previously described.

When a new workpiece has been placed in the clamp ing unit 16 by thereturning spindle 'headunit 25, the sleeves 52 and 53. are 'againrotated to pivot the end clamps 46 and 47 to their'upright position, asshown in Fig. 2. At this time the piston 60 is moved by hydraulicpressure to the left to effect longitudinal movement of the end clamp 47towards the end clamp 46. The end clamp '47-will.rnove the workpiecewithitnntil the workpiece .is-in contact with the end tclamp-46. topositiomthe workpiece in .a predetermined desired: longitudinalposition. Continuedhydraulicpressure-on the piston .60 willeifectivelyclamp the workpiece between the end clamps 46 and-47.

Slide clamping pressure .is exerted by the use of the four side clamps48, 49, 50 and 51. Of these,'clamps 48 .and 49tare stationary. andzserveto fix the position of the workpiece .1 laterally, asrpreviously:mentioned. [End clamps 15,0 and .51 aremovable to urge the workpieceagainst the:stationary clamps, .to position the workpiece iniaipredeterrnined desired lateral position and tto exert a.grippingirpressure upon it.

The side clamps 50 and 51 are actuated by apiston movable 'within acylinder 64 into which hydraulic fluid under pressure may "beselectively admitted to either side of the piston to efiectpivotal-movement of the clamps 50 'andu'51 into or out of -clampingengagement. The piston '65 within the cylinder 64 is connected to apiston rod 66 having a gear rack 67 formed thereon for'coaction with-aspurgear 68, as b'est shown in Figs. 2 and 3. The-spur gear 68 iskeyedto a shaft69-journalled'in-upright'brackets 70, 70:1,70b and 70cintegrally formed'with the base plate 71a of the clamping unit frame.The shaft69- also carries spiral gears 71 and 72 which are secured tothe shaft for rotation with it. The spiral gears .71'and72 are utilized'to transmit .power to separate gear systems, each gear system beingoperably connected to pivot its associated side clamp into or out ofclamping engagement.

A's can'be seen in Fig. 2, the shaft 6.9 is so disposed in the brackets70,, 70a, 70b and 70c as to have limited axial movementfin bothdirections as defined by the width ofj'the spacesi69a and69b whichexist'between the bracket 70 and the gear 71 and the bracket 70a andthe. gear 71, respectively. Inasmuch as the gear systems contiguous.tothe spiral gears .71 and 7.2.are the same only that system associated-withthe spiral .gear 71 and. side clamp 51. will he described in.detail.

.Asshown'inhigsl and 4, thespirahgear 71 is in meshing engagement with-aspiral gear .73 keyedtoashaft 74 for rotating atcam 75 secured to theend-of the shaft. Mountedontheshaft 74-on-eitherrsideroftthe gear .7-3are apair of spacers 72a .and;72b. which;etfectively-pteventaxialmovement ofnthepgear73 and fthexshaft 74. The cam 75.:is v:disposed:to fit within -a1 slot'76a formed in a rod'7/6rand is adapted -'to thein constant-contact with an arcuatesurface? idefining one end o'f theslot. Tothis end, a roller78'mountedon'aplunger '19 is'carriedwithin ahollow-portion 79a'formedin therod76. and which extendsfromoneenddhereof and communicates with a surface definingjthe oppositeendof the slot'7.6 a. A spring 811, one end of which is engaged within-acavity;81 formed in, the plunger 79, is compressed between .thebase.0f.the cavityand afaceSS of a tension adjusting inut.84 threaded in theend of the rod 76. The spring 80 urges the roller 5 78 against theperipheral surface of the cam 75, and with the cam as a base, urges therod 76 to the right, as viewed in Fig. 4, so that the surface 77 on therod 76 is also kept in constant contact with the peripheral surface ofthe cam 75. Therefore, any change in the distance between the peripheralsurface of the cam in contact with the surface 77 of the rod 76 and theaxis of the cam will be reflected in a varying linear movement of therod 76.

As previously stated, the shaft 69 with the gears 68, 71 and 72 is soconstructed and arranged as to be movable axially in either direction.Therefore, if either of the clamps or 51 contact the workpiece ahead ofthe other the movement of its driving cam will stop as well as theassociated spiral gear 73. The shaft 69 with the gears 68, 71 and 72will drift towards the other clamp until that clamp also contacts theworkpiece whereupon both clamps will exert a simultaneous clampingpressure on the workpiece.

Assuming that the clamp 51 contacts the workpiece first, its actuatingcam 75 along with the cam driving spiral gear 73 and shaft 74 will stoprotating. However, the spiral gear 71 will continue to be rotated andsince the shaft 69 is freely movable axially, the rotative force of thespiral gear 71 will move the gear 71 and shaft 69 to the left, as viewedin Fig. 2. This leftwardly movement of the shaft 69, of course, movesthe spiral gear 72, also to the left. However, since the clamp 50 hasnot contacted the workpiece, its driving cam 75a with its driving spiralgear 73a and shaft 74:: continues to be rotated. When the clamp 50contacts the workpiece the resisting forces acting against the spiralgears 71 and 72 are equalized and the spiral gear 71 can no longerexpend its force in moving itself and the shaft 69 left wardly. Sincethe power input through the gear 68 will be continuing, the spiral gears71 and 72 will engage their associated clamps 50 and 51 with theworkpiece with an equalized pressure, moving the workpiece against thestationary clamps 48 and 49 and clamping it in the desired position.

Movement of the rod 76 is reflected in the side clamp 51, which ispivoted about a pin 85, along with its components, a jaw 86 and itsserrated insert 87. Fixed to the lower end of the clamp 51 is a fork 90which fits over a tongued end 91 of the rod 76. The inner surfaces abutconvex surfaces 92, one of which can be seen in Fig. 4, provided on theend of the rod 76 at each side of the tongue 91 at its base. The tongueend 91 of the rod '76 is kept within the fork 90 by a pin 93. In thismanner any movement of the rod 76, slidably mounted in a suitablebushing 94 and protruding out of a cover plate 95, will be transmittedto the clamp 51.

A duplicate clamping unit 17 of identical construction as the clampingunit 16, described in detail above, is attached to the bed 15 adjacentto the clamping unit 16. Inasmuch as the parts and operation of the twounits are identical a detailed description of clamping unit 17 isomitted.

Adjacent the clamping unit 17, is the conveyor unit 19 for removing theworkpiece from the milling machine and is comprised generally of aconveyor frame 96 on which a plurality of rollers 97 are rotatablysupported. A workpiece in the clamping unit 17 is removed therefrom byaction of a transfer pin 45b carried by the spindle head unit 26, beingengaged in the workpiece in the clamping unit 17. At the same time atransfer pin 45a also carried by the spindle head unit 26, engages withthe workpiece in the clamping unit 16 and the transfer pin 45 carried bythe spindle head unit 25 engages with a workpiece released from theconveyor 18. With the several transfer pins thus engaged, the returnstroke of the spindle head units 25 and 26 to the position shown in Fig.1, will advance a new workpiece from the conveyor 18 into the clampingunit 16, the workpiece in clamping unit 16 will be advanced to theclamping unit 6 17, and the workpiece in clamping unit 17 will be movedto the conveyor 19.

The transfer pins are all moved simultaneously through the operation ofa gear rack 142 formed on each pin in position to mesh with cooperatingspur gears 143 keyed to a rod 144 to rotate with it. The rod is revolvedby a spur gear 145 which is rotated by an actuating gear rack 146provided on the end of a piston rod 147 secured to a piston (not shown)in a cylinder 148 attached to the spindle head unit 25. The rod 144 issupported on the spindle head units 25 and 26 by bearings 149 and 150mounted on plates 151 and 152 secured to the spindle head unit in aconventional manner.

All clamping of the clamping units and movements of the saddle and thetransfer pins are the result of hydraulic pressure being applied tovarious hydraulic cylinders which actuate the movements. The oilpressure in the hydraulic circuit is maintained by two double pumps 153and 154 driven by an electric motor 155 as best shown in thediagrammatic view of Fig. 5. I

The hydraulic fluid is drawn from an oil reservoir 156 through an oilfilter 157 and intake pipes 158 into the double pump 153 where the fluidis pumped into the circuit under pressure. The fluid leaves the doublepumps 153 through oil lines 159 and 160. The line 159 communicates witha line 161 which is connected to a solenoid valve 165. Meanwhile thefluid in the line 168 is partially channeled into a pilot line 180 whichis in communication with the line 160, the function of which will besubsequently described. The fluid remaining in the line passes through acheck valve 162 into a line 161 and thence into a branch line 185. Thebalance of the fluid in the line 161 combines with the fluid flowingfrom the line 159 with the excess fluid returning to the reservoir via arelief valve 163 and line 199.

A solenoid 164 of the solenoid valve 165 is energized manually, throughan electric switch (not shown) for the purpose of positioning the valveto permit the fluid in the line 161 to pass through the valve into aline 167. From the line 167 the fluid flows into lines 168 and 169 whichare in communication with the line 167 and with the hydraulic cylinders57 of the double acting pistons 58. The fluid pressure in the cylinders57 causes the pistons to move thereby effecting rotation of the sleeves52 and 53 to pivot the end clamps 46 and 47 into an upright position aspreviously described.

After the end clamps 46 and 47 are pivoted to the upright position, thepressure in the line 167 increases until it reaches a predeterminedvalue sufficient to actuate a sequence valve 170 which is connected tothe line 167. The fluid will then pass through the valve 170 to the rodends of the pistons 60 in cylinders 173 via lines 171 and 172. The fluidpressure move the pistons 60 inwardly causing the end clamps 47 securedto the rods 54 to move towards the end clamp 46 to clamp the workpiecein the clamping units 16 and 17 in endwise position.

Some fluid from the line 171 passes into a branch line 174 to actuate asequence valve 175, letting the fluid from the line 167 pass through toa line 176 leading into the transfer pin cylinder 148 to eflect rotationof the rod 144 which moves the transfer pins 45, 45a and 45b,simultaneously out of engagement with the workpieces.

As the transfer pins are being moved out of the workpieces, a limitswitch 177 is tripped by a cam on the piston rod 147 energizing asolenoid 179 of a solenoid valve 178 to position an internal valve (notshown), to allow fluid pressure in the pilot line 180 to move a mainvalve (not shown) within the solenoid valve into a position where fluidfrom one of the pumps of the double pump 154 may flow to the line 184via line 181, check valve 182 and a line 183. At this time fluidpressure in the line 161 has built up to a predetermined value to open asequence valve 186 whereupon fluid from the line 161 flows through theline 185 and sequence valve 186 to combine with the fluid flowing inline 183. The combined fluid now flows 7 through theisolenoid .valve1'18 :into :line ilfi and thence to the side clamp hydraulic cylinders64. toapivotstheiside clamps and 51 into clamping engagement with theworkpieces.

When the pressure in the line '1'84.reaclies:a:prcdetermined value, apressure switch 1187 operatively connected to be actuated by pressurefromtheline 184 isrclosed-to energize a solenoid 188 of. a1solenoidvalve .189. The solenoid "188. will move a pilot valve not shownywithinthe solenoid valve :189 into position .so thatxfluid in another branchofline130=can position the internal main valve (not shown) ofthesolenoid-valve .189 to permit fluid from one of the pumps ofsthedoublecpump 154 to flow "through a'feedline '190ithrough thesolenoidvalve 189 'into ayline 19.1. T he feedline 190 isialsoconnectedtoanother: reliefvalve .163, similar .toitherclief valve 163 associatedwith the pump .153, to allow fluid to return to thereservoir throughavreturnlline 1 99.

The hydraulic CiICllltifOT operating the clampingrunits of the presentinvention is associated with :thehydraulic circuit for controlling thermovement of the movable membersof the machine toolinthe=presentiembodiment, and the, complete circuit is'therefore.described to clarify the. operation of the clamping :units. It is,however, to be understood that thesclamping units of the presentinvention may operate in conjunction with the hydraulic circuits ofother machine tools or may be operated by an independent hydrauliccircuit without in any. way .de tracting from its etlicicncy.

The oil in the line 19.1.is utilizedto actuate the saddle in its path ofmovcmcntand to this end flows to. a piston and cylinder mechanism 109operably connected to the saddle to effect the feeding movement of thesaddle. The exhaust fluid from the mechanism l09 isreturned to thereservoir throughlines 197, a metering control valve 165 is energized,causinglfluid to flow from the line 161 into a line 203 to the transferpin hydraulic cylinder 148 to. lower pins 45, 45a and 45b intoengagement with the workpieces for transferring them to the nextstations. Si hen the pinsare in-place, the fluid pressure in. the-line28.3 builds up until the. fluid is passed through a sequence valve 20-into, anroiLline 20510 be conducted tothe end clamp hydrauliccylindersclZS where the pressure is exerted on the head end side of thepistons to .move the ,piston rods 54 outwardly releasing the end iclamping pressure. Oil line 205 is also connected to the'hydrauliccylinders 57 to actuate thepistons 58 for pivoting the end clamps 46 and47 to clear the pathof movement of the workpieces.

Meanwhile, a pressure switch 206 connected into the line 205 isactuatedwhen the .pressure inlthe:line reaches a predetermined value. The switch206 :upon being actuated closes an electric circuit which energizesa'solenoid 207 of the solenoid valve 178 to actuate its internal pilotvalve, so that fluid in the line 183 flows through the valve into a line203 to the side.clarnpthydraulic cylinders 64 for the purpose ofshifting their pistons '65 and piston rodsfid to elfect arelcaseoftthcsidecclamping pressure.

The. movement of the pistons 65 and *their associated piston rods 66 aswell as the movement of the pistons 58 to release the side clamping:pressure and effect the pivotal movement ot'sthe. endclamps 46 and 47to provide clearance for the workpiece, results'in the closing o'fa pairof limit-switches 20-9 and 210, by 'a -cam z-lil on the rods 66 of theside clamping cylinders; and

also the :closing-rof a.pair'of. limitswitches; 212 and 213 bya'cam"214,1-on Stile double acting pistons 58. Upon closing of theselimit switches, a. solenoid 215 of rthe solenoid valve139:1St8l16l'giZ3d, to effect .opening of the solenoid .valve to a line216v connected to the cylinder 109 to retract :the saddle to its initialstarting position. The movernent of thessaddle .to its starting positionis accomplished :at. a rapid traverse rate by means of-increasing thevolume .of fluid .to the :cylinder mechanism idflrthrongh :the operationof a sequence and check valve 217. The valve 217 is actuated 'bypressure from the line 183, which is 'connected'to the valve by aline.218. When thewpressureinrthe line 218 reaches apredeterminedlvalue, itactuates thevalve 217 permitting the fluid toflow through the .valve into the line 216, through the checl; valve 219and into the line 197 where it flows to the hydraulic. saddleactuator109. When the'piston rod 110 of the hydraulic mechanism 109 nears theend of its return stroke a limit :switch 220 is tripped by a camldllpthereonzto cause -..deenergization of the solenoid 215 of thesolenoid valve'189 to complete thecyclc.

A description ofzthe electrical system is not included herein as it is.not considered to be necessary for a clear understandingof the presentinvention. A detailed description of the electrical. circuit appears inour aforementioned -U. S. BatentNo. 2,749,811 to which:reference may behad if it is. so desired.

From the foregoing explanation of the operation of the illustratedembodiment of the invention, it is apparent that there has been provided.an improved clamping apparatus capable of accurately positioning andsecuring relatively large workpieces'with substantially equal pressurebeing applied to the workpiece by the several clamping elements of theapparatus even though the dimensions of the workpieces may vary and thatis adaptedrto grip the workpiece on all four sides .but does notinterfere with themovement oftheworkpieces from one station toanotherina'transfer machine tool.

Although the illustrative embodiment of the invention has been describedin considerable detail for the purpose of disclosing a practicaloperative structure whereby the invention may be practicedadvantageously, it is to be understoodithat the particular apparatusdescribed is. intended tobe illustrative only, and that the variousnovel characteristics of the invention may be incorporated in otherstructural forms without departing from the spirit and scope of theinvention as defined. in the subjoined claims.

The principles, of this invention having now been fully explainedinconnection with the foregoing, description, we hereby claim as ourinvention:

1. Ina clamping imechanismadapted to secure a workpiecetoroperationzupon by a cutter, a base having a surface upon which theworkpiece to be secured rests, a sleeve rotatably mounted in said base,a second sleeve rotatably mounted in said base in axial alignment withsaid first sleeve and interconnected with said first sleeve for unitaryrotation with it but movable axially with respect .to it, anxendclampsecured to said first sleeve at the end of said base inpositionto engagethe end of the workpiece as it rests upon said surface of the base, asec-ondend clamp fixed to said second sleeve at the other endof .saidbase: in position to engage the other end of the workpiece as it restsupon the surface of t the base, both of said endclamps being mounted onsaid sleeves imposition so that when the sleeves are rotated the endclampsmove with them to enable them tobe pivoted to a position belowsaidsurface .of the baseto clear. a path for the workpiece for slidingitonto ,or off, of the base, and a rod extending through both of saidsleeves and securedto said second axially movable sleeve, said rod beingmovable'axiallytor moving said second sleeve and its associated endclamp into engagement with the end .of'the workpiece for'exerting apressure upon it to clamp the workpiece between the two end clamps.

2. In a clamping mechanism adapted to'secure a workpiece for operationupon by a cutter, a base having a surface upon which the workpiece to besecured rests, a sleeve rotatably mounted on said base, a second sleeverotatably mounted in said base in axial alignment with said first sleeveand interconnected with said first sleeve for unitary rotation with itbut movable axially with respect to it, an end clamp secured to saidfirst sleeve at the end of said base in position to engage the end ofthe workpiece as it rests upon said surface of the base, a second endclamp fixed to said second sleeve at the other end of said base inposition to engage the other end of the workpiece as it rests upon thesurface of the base, both of said end clamps being mounted on saidsleeves in position so that when the sleeves are rotated the end clampsmove with them to enable them to be pivoted to a position below saidsurface of the base to clear a path for the workpiece for sliding itonto or off of the base, a rod extending through both of said sleevesand secured to said second axially movable sleeve, said rod beingmovable axially for moving said second sleeve and its associated endclamp into engagement with the end of the workpiece, and a piston andcylinder mechanism connected to said rod for actuating it in its axialmovement to move said second end clamp into engagement with theworkpiece for exerting a pressure upon it to clamp the workpiece betweenthe two end clamps.

3. In a clamping mechanism adapted to secure a workpiece for operationupon by a cutter, a base upon which the workpiece to be secured rests,an end clamp mounted on each end of said base for pivotal movement sothat they may be pivoted below the surface upon which the workpiecerests to permit the workpiece to be slid onto the base, one of said endclamps being also movable laterally to exert an end pressure upon theworkpiece for clamping it between said end clamps, a pair of side clampsrigidly secured to one side of said base in position to engage the sideof said workpiece, and a second pair of side clamps pivotally mounted onthe other side of said base in position to engage the side of saidworkpiece so that they may be pivoted to exert a side pressure upon theworkpiece to clamp it between the two pair of side clamps, whereby aclamping pressure is applied to the workpiece in two directions.

4. In a clamping mechanism adapted to secure a workpiece for operationupon by a cutter, a base having a surface upon which the workpiece to besecured rests, an end clamp mounted on each end of said base for pivotalmovement enabling them to be pivoted so as not to extend above thesurface upon which the workpiece rests to clear a path for the workpiecefor sliding it onto or ofi of the base, one of said end clamps beingalso movable toward and away from the base to engage the workpiece andclamp it between said end clamps, and power means connected to move saidend clamp toward the base for exerting a pressure upon the workpiece toclamp it in position, whereby the workpiece may be securely clamped bythe end clamps which can be pivoted out of their operating position toclear a path for sliding it onto or olf of the base.

5. In a clamping mechanism adapted to secure a workpiece for operationupon by a cutter, a base having a surface upon which the workpiece to besecured rests, a first sleeve rotatably supported within said base, afirst end clamp secured to said sleeve for rotation therewith, a secondsleeve rotatably supported within said base in axial alignment with saidfirst sleeve, said second sleeve being adapted to move axially relativeto said first sleeve, means operably connecting said first sleeve andsaid second sleeve together in a manner that rotational movement of onesleeve will effect rotation of said other sleeve, a second end clampsecured to said second sleeve for rotation therewith, a piston andcylinder mechanism mounted within said base and operably connected torotate said sleeves to pivot said end clamps into endwise positionrelative to the workpiece, and a second piston and cylinder mechanismcarried by said base and operably connected to move said second endclamp relative to said first end clamp, whereby the workpiece may besecurely clamped between said end clamps.

6. In a clamping mechanism adapted to secure a Workpiece for operationupon by a cutter, a base having a surface upon which the workpiece to besecured rests, a pair of side clamps rigidly secured to one side of saidbase in position to engage the workpiece thereon, a second pair of sideclamps movably supported on the opposite side of said base in positionto be engageable with said workpiece, a gear transmission carried withinsaid base and operably connected to actuate said movable side clampsinto and out of engagement with said workpiece, and a piston andcylinder mechanism operably connected to drive said gear transmission.

7. In a clamping mechanism adapted to secure a workpiece for operationupon by a cutter, a base having a surface upon which said workpiece tobe secured rests, a pair of side clamps secured to one side of said basein position to engage the workpiece, a second pair of side clampspivotally mounted on the opposite side of said base in position toengage the workpiece, a pair of gear transmis- 31 sions carried withinsaid base, a pair of cams each operably connected to be rotated by oneof said gear transmissions, a pair of rods slidably supported on saidbase, each of said rods being operably connected to one of said pivotalside clamps, said rods being connected to be movable axially by saidcams, means operably connected to urge said rods into engagement withtheir associated cams at all times, and a piston and cylinder mechanismin said base operably connected to drive said gear transmissionssimultaneously.

8. In a clamping mechanism adapted to secure a workpiece for operationupon by a cutter, a base having a surface upon which said workpiece tobe secured rests, a sleeve rotatably mounted in said base, a secondsleeve rotatably mounted in said base in axial alignment with said firstsleeve and operably connected to said first sleeve for rotationtherewith, said second sleeve also being movable axially independentlyof said first sleeve, an end clamp secured to said first sleeve inposition to engage the end of said workpiece as it rests on said base, asecond end clamp secured to said second sleeve in position to engage theopposite end of said workpiece as it rests on said base, said end clampsbeing positioned on said sleeves in a man-- ner to enable them to bemoved below the surface of said base to clear a path for the workpiecefor sliding it onto or off of the base, power means operably connectedto rotate said first sleeve, an axially movable rod extending throughboth of said sleeves and having one end secured to said axially movablesecond sleeve, and power means connected to the other end of said rod tomove said rod and thereby said second sleeve with its associated endclamp into engagement with the end of said workpiece for exerting apressure upon it to clamp the workpiece be tween the two end clamps.

9. In a clamping mechanism adapted to secure a work piece for operationupon by a cutter, a base having a surface upon which the workpiece to besecured rests, a pair of side clamps secured to the side of said base inposition to engage the side of the workpiece as it rests upon thesurface of said base, a pair of movable side clamps mov' ably mounted onthe other side of said base in position to be engageable with theopposite side of the workpiece to exert a side pressure upon theworkpiece to clamp it between the two pairs of side clamps, a pair ofgear transmissions within said base, a pair of cams, each of said camsbeing operably connected to be rotated by one of said geartransmissions, a pair of rods slidable carried within said base, saidrods each being provided with a slot for receiving one of said cams,means to urge said rods into constant engagement with said cams, meansoperably connecting said rods with said movable clamps, and powerzgarsmoa that they rotate together but permit axial movement: of i saidsecond sleeve relative to said first sleeve, clamping elements securedto :said sleeves in position to be rotated from a,position belowtheworkpiecesupporting surface of said base to'a positionadjacent to:thecnds of a workpiece supported on said.base,.power.meansloperabiyconnected :to move one of saidclamps'towards said base in a manner toengage the workpiecel'between saidclamps and to exert a clampingpressure thereon, and power meansoperably connectcdto rotate saidsleeveswhen the clamping pressure is released.

11. In a clamping'mechanism-adapted'to secure aworkpiece for operationupon by a cutteryabase upon which the workpiece to be secured rests; endclamps mounted on each end of said base for pivotal movement so thatthey may be pivoted below the surface upon which the workpiece rests topermitthe workpiece to he slid onto the base, one of said end clampsbeing also movable laterally to exertvan end pressure upon the workpiecefor clamping it betweensaid end clamps; a pair of stationary side clampsrigidly secured to one side of each base in ,position to engage .theside of said workpiece; a second pair of side clamps pivotally mountedon the other side of said base in position to be pivotally moved intoengagement with the opposite side of said workpiece; equalizing meansoperably connected to actuate said movable side clamps into engagementwith said workpiece in a manner that said side clamps will operatesimultaneously to exert an equal clamping pressure on said workpiece;and power means operably connected to actuate said equalizing means.

l2. In a clamping mechanism adapted to secure a workpiece for operationupon by a cutter; a base having a surface upon which said workpiece tobe secured rests; a pair of stationary side clamps secured to one sideof said base in position to engage the workpiece; a pair of movable sideclamps pivotally mounted on the opposite side of said base in positionto be engageable with the workpiece; a pair of actuatingmembers in saidbase operably connected to said movable clamps to move them intoengagement with said workpiece; cam means associated with each of saidactuating members to effect movement of said actuating members;resilient means operably connected to maintain each of said actuatingmembers in constant engagement with their associated cams; a pair of camshafts rotatably supported in said base and restrained from axialmovement, said cams being secured to said shafts for rotation therewith;a spiral gear keyed to each of said cam shafts; a power shaft supportedin said base for rotational and axial movement; a pair of spiral gearskeyed to said power shaft in position to mesh with the spiral gears onsaid cam shafts;'and power means operably connected to rotate said powershaft in either direction; whereby when said power shaft is rotated inone direction said cams are rotated to move said actuating members topivot said movable clamps into engagement withssaid 'Mnrkpkcqiind asone- :or "the other it of said clampsengages the -workpiece'its-associated eam shaft andthetsp'irztlgearikeyed theretostoprotatingcausing the cooperatingzspiral gear= on said power-shaft to-movesaid power shafttowards;said other movable clamp to effect acontinuedi'pivotalmovement of tlie othr movable clamp until itengagestsaid'workpiece whereuponthe power will bectransmitte'di throughbo'tlr of said camshafts to said clamps :.to:efiect anequalizedclamping"pressure on said workpiece 13. in a clamping mechanism :adapted tosecure a workpiece for operation: upon by a' butter, 21 base upon whichthe workpiece toh'e secured rests, anen'd clamp mounted on each .end totsaid ibase -for pivotal movement so that they may-beipivot'edibelowthe:surface upon which the workpiece rests ato permit the workpiece tobe slid onto the base, :oneiof said end lclampsbeing also movablelaterally to exert a'nend lpressure upon the workpiece for clamping it.between iSflidi=6fld clamps, a-pairof side clamps rigidly rsccuredltooneside ofsaid base in position to engage thessidel ots'said workpiece,a second pair of side clamps ipivotallyrmounted on the other side ofsaid base in tposition'to enga'ge theiside of said workpiece, andequalizing means operably iconnected ito actuate said pivotal sidelclampsz'intos-simultaneous clampingengagement with said-workpiece. I

14. In a clamping mechanism for securing a workpiece; a base adaptedrtosreceive the workpiece; a pair of movable, side clampswmounted on oneside of said base in position to engage/the workpiece; immovable meanstfixed to-the opposite side ofxsaid base and adapted to be abutted bythe: workpiece to serve as a stop for locating the workpiece in a-.desired position and enable said movable-side cla'mps-to'ap'plypressure for clamping the workpiece; a clamp shaft nfor each ofsaidmovable clamps rotatably supported 'insaid base and restrained fromaxial movement, each of said clamp shafts being operably connected toactuate its associated movable clamp into or out of engagement with theworkpiece; a spiral gearsecured-on each of saidclump shaftslfor rotationwithit; a power shaft supported in said base for rotational and axial'movement; a .pair of spiral gears secured to said power-shaft and; inmeshingengagement with said spiral gears on said clamp shafts; and powermeans operably connected torotate said power shaft in either direction;whereby when (said power'shaft is rotated in one direction-said clampshafts are rotated to move their associated :movable clamps intoengagement with the workpiece to clamp the workpiece against saidimmovable means, and .as one-or the-other of said clamps engages theworkpiece its-:associatedlclamp shaft and the spiral .gear thereon stoprotating causing its cooperating spiral gear onsaidj power shaft to movesaid power shaft toward the other movable clamp to eifect continuedmovement of the other movable clamp until'it engages the workpiecewhereupon. the power of said power shaft will be transmittedthrough bothof said clamp shafts to said clamps simultaneously to effect. anequalized clamping pressure on said workpiece.

References Cited in the file of this'pa'tent UNITED STATES PATENTS

